Tag Archives: IBC

Structural Design of Stairs With Cutout Stringers

Structural Design of Stairs With Cutout Stringers

Loading requirements for stair stringers are called out for in IBC (International Building Code) Table 1607.1. For one and two family dwellings, uniform live load is 40 psf (pounds per square foot) and 100 psf for all other occupancies. Although not expressly stated, one would assume one and two family dwellings would also incorporate accessory buildings (garage/shop or similar) on a property with a dwelling (basic IRC – International Residential Code) present.

IBC Section 1011.2 requires stairs to be 44 inches in width, with exception 1 allowing for a 36 inch width provided stairs serve an occupant load of less than 50.

IBC Section 1011.5.2 specifies maximum stair rise as 7 inches and minimum run as 11 inches. Exception 3 allows rise to be 7-3/4 inches and run as 10 inches for R-3 occupancies, within dwelling units for R-2 and Group U when an accessory to either of these (basically an IRC qualifying structure). Some jurisdictions have amendments allowing for greater rises and lesser runs.

Stair stringers act as beams, where top is attached to an appropriate member by means of a Simpson LCS bracket (or equivalent) and bottom is resting upon a wood or concrete floor.

Looking at an exception 3 above rise and run, would cut triangles 4-1/2” deep into a 11-1/4 inch 2×12 stringer, leaving 6-3/4” of ‘meat’ remaining.

How far can a 2×12 stringer then span in a residential application?

Checking for bending only:

SQUARE ROOT OF [8 x Sm (Section Modulus of 1.5” x 6.75” x 6.75” / 6 = 11.39) x Fb (Fiberstress in bending, for #2 SYP = 750, SPF = 850, HemFir = 875, DFir = 900)] / (40 psf live load + 10 psf dead load) x 36” width stairs/2 (one stringer on each edge of stair width)

For SYP (Southern Yellow Pine) = 8.71’ (or 8’8”). This span is measured horizontal to ground and is measured from centerline of required bearing area at each end.

Checking for Deflection

Allowable = 104” / 360 = 0.289”

Maximum = (5 x (50 psf/12 x 1.5’) x 104”^4) / (384 x MOE x I)

MOE (Modulus of Elasticity) = 1,400,000 for SPF or SYP; 1,600,000 for DFir; 1,300,000 for HemFir

I = b x d^3 / 12 = 1.5” x 6.75”^3 / 12 = 38.44

(5 x 6.25 pli x 104”^4) / (384 x 1,400.000 x 38.44) = 0.177” <= 0.289” therefor OK

For greater spans, a 2×6 #2 can be applied alongside 2×12. Fb value of lesser member must be used (even though 2×6 has a greater individual strength):

Bending test:

SQUARE ROOT OF [8 x (11.39 + 7.5625) x 750] / (50 x 18”) = 11.24’ (rounding down to 134”)

Checking for Deflection

Allowable = 134” / 360 = 0.372”

Maximum = (5 x (50 psf/12 x 1.5’) x 134”^4) / (384 x MOE x I)

I = b x d^3 / 12 = 1.5” x 6.75”^3 / 12 = 38.44 for notched out 2×12 plus 20.8 for a 2×6

(5 x 6.25 pli x 134”^4) / (384 x 1,400.000 x 59.24) = 0.316” <= 0.372” therefor OK

Need to span even farther? Let’s add another 2×12 with a 2×6 on each side in center of tread. Center stringer supports twice load of outer stringers.

SQUARE ROOT OF [8 x (11.39 + (2 x 7.5625)) x 750 x 1.15] / (50 x 18”) = 14.258’ (171”)

But wait, where did 1.15 come from? When three members are combined or members are 24 inches on center of less, Cr (Repetitive member factor) is equal to 1.15.

Checking for Deflection

Allowable = 171” / 360 = 0.475”

Maximum = (5 x (50 psf/12 x 1.5’) x 171”^4) / (384 x MOE x I) I = 38.44 for notched out 2×12 plus 2 x 20.8 for two 2×6 = 80.04

(5 x 6.25 pli x 171”^4) / (384 x 1,400.000 x 80.04) = 0.621” > 0.475” therefor NOT OK

Even though this combination works for bending, it is beyond deflection limitations. Solution is to place internal stringers at third points.

Ice and Water Shield with Threw Screwed Steel Roofing

Ice and Water Shield with Threw Screwed Steel Roofing

Making sense of Building Codes can be a daunting task, even for Building Officials. Post-frame construction is vaguely mentioned, at best, within Building Codes, leading to at best head scratching and at worst total confusion.

Ice and water shield is a waterproof membrane used to protect roof from ice and water damage. Its main purpose is to protect roof decking (plywood, oriented strand board – OSB, etc.) if water gets underneath roofing materials. Also known as a roofing underlayment, this rubberized slip-resistant product is “peel and stick” and self-adheres to roof deck’s surface, preventing it from flying up during high wind events.

Most post-frame buildings are constructed with threw screwed steel roof panels directly over purlins. So how do Codes apply to this circumstance?

2021 IBC (International Building Code) addresses Metal Roof Panels in Section 1507.4
“The installation of metal roof panels shall comply with provisions of this section.” (2021 IRC (International Residential Code) Section R905.10).

1507.4.1 Deck Requirements (IRC R905.10.1)
Metal roof panel roof coverings shall be applied to a solid or closely fitting deck, except where roof covering is specifically designed to be applied to spaced supports.” Metal roof panels on most post-frame buildings are designed to be applied over spaced supports (purlins)

1507.4.5 Underlayment (IRC Section R905.10.5) and High Wind.
Underlayment shall comply with Section 1507.1.1″ (IRC Section R905.1.1)

1507.1.1 Exception 3. “Structural metal panels that do not require a substrate or underlayment” (Note: this exception is not listed in the IRC, implying an underlayment must be used when V => 140 mph) Interestingly enough, the 2020 Florida Building Code, Residential, has an underlayment exception, “Compliance with Section R905.1.1.1 is not required for structural metal panels that do not require a substrate or underlayment.”

No substrate is required (steel fastened directly to purlins).
Table 1507.1.1(1) Underlayment Types (Table R905.1.1(1) in 2021 IRC)
Metal roof panels where maximum basic design wind speed V <140 mph are to be have underlayment per “Manufacturer’s instructions”

Manufacturer does not specify an underlayment must be used.
Metal roof panels where maximum basic design wind speed V => 140 mph are to meet ASTM D226 Type II or ASTM D4869 Type IV (IRC allows ASTM D4869 Type III)

ASTM D226 Type II is authentic asphalt saturated organic felt (also known as 30# felt) underlayment used as a breathable secondary weather resistant barrier when applied over roof deck prior to installation of primary roofing product.

ASTM D4869 Type IV affords same features as ASTM D226 Type II plus has a tear strength of 0.9 lbs/ft for both machine direction and cross machine direction of sheet; a 6% (as compared to 4%) loss on heating/behavior on heating for 5 hours at 221 degrees F; has liquid water transmission able to pass four hour water test on a 14 degree (3/12 slope) inclined roof; has a maximum dimensional stability of 1.75% both machine and cross direction from low to high humidity; has a 150% minimum saturation % by weight; a 2% moisture minimum % by weight at time of manufacture and a 70% minimum saturation efficiency % by weight.

However, we must refer in IBC governed buildings, once again, back to Section 1507.1.1 Exception 3 (yes, the Codes seemingly go around in circles).
1507.1.2 Ice Barriers (IRC R905.1.2)
“In areas where there has been a history of ice forming along the eaves causing a backup of water, an ice barrier shall be installed for asphalt shingles, metal roof shingles, mineral-surfaced roll roofing, slate and slate-type shingles, wood shingles, and wood shakes.”

Note: Metal roof panels are specifically not included.

Information on Codes and Shouses

Information on Codes and Shouses

I have to admit it was rather flattering to have Southwest Iowa’s Planning Council reach out to me regarding information on Codes and Shouses recently.

“Hello. My name is Ashley and I’m a community development specialist with Southwest Iowa Planning Council out of Atlantic, IA. I am currently working on some Zoning and Building codes for smaller towns and they want to include zones and/or building codes for shouses. Since this is relatively new to this area, within city limits at least, I was curious what issues your company has come across regarding codes and if you had any sample codes from communities that you would be willing to share with me?”

Mike the Pole Barn Guru responds:

Thank you for reaching out to us. We have provided hundreds of post frame shouses and barndominiums in nearly every state. Good news for you (and these jurisdictions) is this project will involve very little extra efforts beyond what is currently in place.

Use of terms such as “pole barn”, “pole building” or “post frame” home, barndominium, shouse or shop/house oftentimes cause permitting waters to become clouded – yet they need not be.

From a Zoning/Planning standpoint – shouses (I will use this as an all encompassing term) should be treated no differently than any other code compliant structural system. Any existing requirements for setbacks, footprint requirements, heights, living area to garage/shop ratios, siding and/or roofing materials, color restrictions, etc., should remain the same as currently adopted. What is important is to not place restrictions upon shouses not existing for other dwellings, as this could end up leading to costly and protracted legal battles.

Currently adopted Building Codes (IRC, IBC, IECC) do not have to be amended for shouses.

In “Effective Use of the International Residential Code”:

Paragraph 4:

“It is important to understand that the IRC contains coverage for what is conventional and common in residential construction practice. While the IRC will provide all of the needed coverage for most residential construction, it might not address construction practices and systems that are atypical or rarely encountered in the industry.”

IRC R301.1.3 Engineered design.

“When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for all buildings and structures, and parts thereof, included in the scope of this code.”

In summary (and in my humble opinion), any shouse outside of IRC prescriptive requirements, should be designed and have structural plans signed by a Registered Design Professional (architect or engineer) to meet or exceed jurisdictional climactic conditions.

Please feel free (or direct any jurisdiction) to reach out to me directly with any questions or concerns.

Fireblocking and Firestops

Fireblocking and Firestops

Hansen Pole Buildings’ Designer Rachel was recently quoting a project for a governmental entity where the contractor requested her to include all provisions for fireblocking and firestops. This led to my deep dive into International Building and Residential Codes (IBC and IRC respectively).

Both have established a means to control fire spread within void spaces created within wood framed assemblies. 

During a fire, flame and heated combustion products can spread via least resistance paths. Certain assemblies, particularly wood frame assemblies, result in concealed voids or cavities within walls, ceilings and attics. These not only affect fire spread, but also make suppression more difficult.

Fireblocking involves field-installed building material use to prevent undetected flame and gas movement to other areas through such concealed spaces. Although such materials are not required to be tested for fire resistance, they are to be installed to slow fire migration, and to contain a fire until it can be suppressed. 

Fireblocks should not be confused with firestops. Firestops are code required when a higher fire protection degree is required, particularly when penetrations through fire resistance rated assemblies are to be protected with a specific material assembly tested under severe fire conditions for a prescribed time period. Unlike fireblocks, firestops purpose is to prevent fire spread from one compartment to another through service and utility openings in floors, ceilings, roofs, and walls. 

Fireblocks are required between floors, between a top story and a roof or attic space, in furred spaces or cavities between studs in wall assemblies, at connections between horizontal and vertical spaces created in floor joists or trusses, soffits, drop or cove ceilings, combustible exterior wall finishes and architectural elements, and at openings for pipes, vents, ducts, chimneys, and fireplaces. 

Fireblocks conform to innumerable configurations, depending on concealed space dimensions and location. IBC Section 718 (Concealed Spaces) is a dedicated section providing description of two concealed spaces and fireblocking. Section 718.2.1 identifies materials acceptable for use as fireblocks. Fireblocks can be constructed of materials such as two inch nominal lumber, structural wood panels, gypsum board, cement fiber board for larger fireblock, and mineral wool or glass fiber batts or blankets, loose fill insulation, and caulks, sealants, and putties for smaller fireblocks. IRC has similar text. 

Frequently, and inevitably, pipes, vents, ducts, and similar items penetrate fireblocks. IBC requires fireblock integrity be maintained in 718.2.1. This may be accomplished by using a sealant, caulk or putty as permitted by 718.2.5. Such materials are required to be approved for such use, and may be either combustible and noncombustible per specific code section and application. Noncombustible sealant use would address both conditions where either combustible or noncombustible are required, but not vice versa. Therefore, a noncombustible material would serve a broader use range than a combustible sealant, caulk or putty. (Noncombustibility shall be determined by testing to ASTM E 136 per other code sections).

All chimneys and fireplaces are required to be fireblocked by code. Factory-built chimneys and fireplaces are required to be fireblocked by code, but are also required to be tested in accordance with UL 103 and 127. Those test methods contain specific information pertaining to fireblocking beyond code requirements. 

In all building codes, designs and location for fireblocking are required to be indicated on construction documents, and are subject to inspection before occupancy in new construction.

Human Habitation Prohibited

Human Habitation Prohibited

“Please be aware that the Land Development Code and adopted Building Codes prohibit the human occupancy of any Accessory Building. This means that buildings such as metal buildings, pole barns, tool sheds, garages, or any other accessory structures shall not be constructed or used for human occupancy. Accessory Buildings are not constructed to the same Building Code standards as Dwellings and therefore a neither suitable nor safe living quarters.”

This quote is from Guidelines for the Permitting, Construction and Use of Accessory Buildings and Structures and is provided by Cass County, Missouri.

Taken all by itself, it would lead one to believe it is impossible to build a barndominium or shop/house in Cass County.

Now….. as the late, great Paul Harvey would have said, “Here is… the rest of the story”:

Planning Departments (also referred to as Planning and Zoning or other similar monikers) can place many restrictions on what can or cannot be built upon any particularly zoned piece of property. These restrictions may include (but are not limited to): Maximum or minimum footprint of dwellings, ratio of living space to garage/shop space, wall and/or overall building heights, setbacks from property lines and other structures, even such things as allowable materials and colors for roofing and siding products.

Yes, I know, it is YOUR property (or yours and your bank) however as long as you have to pay property taxes, you are actually just renting ground from your tax collecting authorities.

What Planning Departments cannot legally do is to prohibit a Code Conforming structural building system from being utilized (and to do so could very well be a Constitutional violation).

Most jurisdictions have adopted International Building Codes (IRC for residential, IBC for other structures). 

IRC has no language in it pertaining to post frame construction, while IBC indeed does.

To follow are IRC excerpts justifying IBC use:

In “Effective Use of the International Residential Code”:

Paragraph 4:

“It is important to understand that the IRC contains coverage for what is conventional and common in residential construction practice. While the IRC will provide all of the needed coverage for most residential construction, it might not address construction practices and systems that are atypical or rarely encountered in the industry. Sections such as R301.1.3, R301., R320.1, M1301.1, G2401.1 and P2601.1 refer to other codes either as an alternative to the provisions of the IRC or where the IRC lacks coverage for a particular type of structure, design, system, appliance or method of construction. In other words, the IRC is meant to be all inclusive for typical residential construction and it relies upon other codes only where alternatives are desired or where the code lacks coverage for the uncommon aspect of residential construction.”

IRC R301.1.3 Engineered design.

“When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for all buildings and structures, and parts thereof, included in the scope of this code.”

In lay person’s terms – a post frame building can be fully engineered to meet with all necessary requirements for meeting structural requirements for snow, wind and other climactic conditions for residential as well as a plethora of other uses.

Should any jurisdiction tell you otherwise – please share this information with them and if they are still unyielding, send me a copy of their written (and approved by City/Town council or county commissioners) documentation and I will politely discuss further with them on your behalf.

Building Code, “Barndos”, and Barn Doors

This week the Pole Barn Guru answers reader questions about which building code applies to a residential “pole barn,” a “Barndo” for Betty, and stall doors for a horse barn.

DEAR POLE BARN GURU: Planning to build in Fremont County, CO. This will be a 2 bedroom residential cabin at 9400 ft. Which building code will apply, Single Family Residential or Pole Barn? JEFF in ATLANTA

DEAR JEFF: There is no “Pole Barn Code”. For one and two family dwellings (R-3) IRC (International Residential Code) will dictate, however it does default to IBC (International Building Code) for structural aspects.

In “Effective Use of the International Residential Code”:

Paragraph 4:

“It is important to understand that the IRC contains coverage for what is conventional and common in residential construction practice. While the IRC will provide all of the needed coverage for most residential construction, it might not address construction practices and systems that are atypical or rarely encountered in the industry.”

IRC R301.1.3 Engineered design.

“When a building of otherwise conventional construction contains structural elements exceeding the limits of Section R301 or otherwise not conforming to this code, these elements shall be designed in accordance with accepted engineering practice. The extent of such design need only demonstrate compliance of nonconventional elements with other applicable provisions and shall be compatible with the performance of the conventional framed system. Engineered design in accordance with the International Building Code is permitted for all buildings and structures, and parts thereof, included in the scope of this code.”


DEAR POLE BARN GURU: How much would it cost for a barndo like the one in the attached picture? BETTY in RADCLIFF

DEAR BETTY: To get an exact price on this, or any, fully engineered post frame barndominium, please call 1.866.200.9657 and speak with a Hansen Pole Buildings’ Designer. Your Building Designer will ask you questions about your building footprint, ceiling heights, building slab-on-grade or over a crawl space or basement, number and size of windows and doors, how you will be insulated, etc. You can easily have changes made to any or all features and dimensions until you arrive at an ideal design solution meeting your family’s wants and needs.

If you do not yet have a floor plan, one can be crafted for you http://www.hansenpolebuildings.com/post-frame-floor-plans/?fbclid=IwAR2ta5IFSxrltv5eAyBVmg-JUsoPfy9hbWtP86svOTPfG1q5pGmfhA7yd5Q


DEAR POLE BARN GURU: I have a metal barn already with two door openings. I am in need of doors for these openings. It is meant a for stall doors for a horse barn. You can kind of see the barn door openings in the photo behind my son. Do you sell just the doors? BRENDA in BERTHOUD


DEAR BRENDA: Thank you very much for your interest. Due to challenges of shipping without damage we only provide doors with our complete post frame building kit packages.

Minimum Design Loads and Risk

Minimum Design Loads and Risk

Model Building Codes, such as IBC (International Building Code), offer minimum design loads for climactic forces such as snow and wind. As building permit issuing agencies adopt codes, within their scope they can establish minimum values for their particular jurisdiction.

Key word here “minimum” – least values a building may be designed for and still obtain a permit to build.

I have long been an advocate for structural designs above minimum requirements. All too often potential new post frame building owners have not had adequate consultative design recommendations enough to find out increases in structural strength are often achieved with minimal investment.

For an earlier article concerning this subject please see https://www.hansenpolebuildings.com/2015/11/bike-helmets-and-minimum-building-design-loads/.

From IBC Section 1604.5, “Each building and structure shall be assigned a risk category in accordance with Table 1604.5. Where a referenced standard specifies an occupancy category, the risk category shall not be taken as lower than the occupancy category specified therein.”

Balance of IBC Chapter 16, including Table 1604.5 may be perused here: https://codes.iccsafe.org/public/document/IBC2018/chapter-16-structural-design.

Buildings representing a low hazard to human life in event of a failure include agricultural facilities. In most jurisdictions, detached garages and shops are also considered to be a fit and these would be considered as Risk Category I. In many areas agricultural buildings are either permit exempt, or do not have to go through structural plan reviews and inspections.  Read a very expensive story about an agricultural building using minimal requirements: https://www.sbcmag.info/content/9/design-load-reductions-risk.

Risk Category I buildings are designed to allow for an occurrence greater than minimum design loads of once in 25 years (or a 4% chance in any given year). In theory, all buildings in this category should collapse within 25 years of construction.

Sobering, isn’t it?

Shopping for a new post frame building and want yours to be last one standing when a storm of a century comes to visit? If so, I would hope whomever you are speaking with offers options of increasing Risk Category from I to II. And bumping up snow loads by 5, 10 or even more pounds per square foot and/or increasing design wind speed by a few more miles per hour.

If you are not offered these options – ask for them. I’d like to have your building be left standing!

Fiberglass Panels, Accurate Info, and Truss Bracing!

DEAR POLE BARN GURU: I have four skylights with old fiberglass panels that are in need of being replaced. I doubt the design of the panel can be matched easily but am wondering if I send you a piece of it if it can be. I understand the way to go is with a polycarbonate, not fiberglass, panel. Thanks DAVE in BAY

DEAR DAVE: As you are finding out, skylights are problematic. Here is some extended reading on why: https://www.hansenpolebuildings.com/2012/01/skylights/.

If indeed you determine the only solution is to replace fiberglass panels with polycarbonate (me, I would replace them with steel panels and be done with the future headache) I would recommend a visit to the ProDesk at your local The Home Depot® as they can order in most anything and it usually comes in freight free, which can prove to be a significant savings.

DEAR POLE BARN GURU: I am buying a building immediately but your website is too intrusive to shop, so I will not be using you. I, like many others, do not like the setup for quotes because in most cases you turn into used car salesmen. BRAD in KNOXVILLE

DEAR BRAD: Thank you very much for your input. In order to be able to provide accurate pricing and design advice to our clients, we do need to gather some basic information. Things like where is your new post frame building to be constructed (so we get the correct climactic loading conditions), as well as how do we best reach you to discuss your proposed project. We get several hundred new inquiries each day, seven days a week, and frankly you are the first to voice an opinion as to our website being intrusive. If you have constructive solutions as to how we can best glean the information needed to be able to best provide our services, without coming across as being ‘intrusive’ we would welcome your input, as we always strive to improve.

Our Building Designers are highly trained professionals whose mission is to assist our clients in the quest for the ideal dream building which melds imagination, budget and available space. Post frame buildings are highly involved, engineered structures, which ideally require a fair amount of interaction between us and the client to arrive at the best design solution. We do not “sell” anything to anyone – we provide the assistance to our clients, as well as the education which enables our clients to invest in The Ultimate Post Frame Building Experience™, should they decide we are the best fit. Most of our clients have spent hours perusing the thousand plus pages of free information on our website and have decided they are going to own a new Hansen Pole Building long before they ever request a quote.


DEAR POLE BARN GURU: Question about my plans. On the drawings, my purlin spacing is noted as 31” OC. On the truss drawing, I see that it says the bracing for the top chord is 24” OC. Am I reading this correctly? 

It states: 

(Switched from sheeted: Spacing > 2-0-0).

and then below it talks about the Bottom Chord: Rigid ceiling directly applied or 6-9-13 oc bracing. What does that mean?


DEAR DAN: Truss drawings are designed without any knowledge of how a particular building is constructed, or what the final bracing system for the entire structure is – the permanent bracing design is left to the engineer of record (see General Safety Notes #2).

You will note the top chord bracing says 2-0-0 purlins then says the maximum spacing is 4-7-0 (least of the three drawings). The 31″ spacing on the plans is far less than the 55″ maximum.

Bottom chord bracing is a function of a maximum L/d (length divided by depth) ratio of L/80 for members in tension (truss bottom chords are in tension as they are preventing the walls of the building from going out). The width of a single 2x member is 1.5″ X 80 = 120″ maximum for a single width 2x member. You will note on the endwalls of the building there is a 2×4 nailed to the face of the bottom chord of the truss. This now makes the member three inches in width so technically it could be braced once every 240″ (or 20 feet). The same goes for the interior double trusses, the three inch width member is good up to 20 feet without being braced laterally.



Prohibition of Pole Barn Construction

The Construction of Pole Barns is Prohibited


This is directly from the White Bear Lake Township (Minnesota) ordinances related to Building Codes, buried deep in their Ordinance No. 8:

5-34. POLE BUILDINGS. The construction of pole barns/buildings is prohibited in the Town.

I found this as a result of an article in the White Bear Press, excerpted below:

“There was also a lengthy discussion regarding pole barns after Planner Tom Riedesel presented several amendments recommended by the Variance Board and Planning Commission.

It all started with a request from residents Don and Janice Stock on Portland Avenue to replace an existing pole barn with a new upgraded design post-frame building. Historically, pole barns have not been allowed by the township due to building quality and aesthetics. However, the quality has improved over the years, so the Board approved the variance with strict standards for construction. Don Stock, whose home is located in the far northeast section of the town, spoke at the meeting to assure the board that the building will match the brown on his home’s natural cedar siding.”

It was reassuring to see the Board approving the variance. Post frame (pole) buildings are Code conforming structures, in accordance with the IBC (International Building Code). It is acceptable for jurisdictions to legislate the exterior appearance of a structure (colors or types of exterior coverings), however it would be a restriction of trade to attempt to prohibit a building system.

I’ve successfully won similar discussions throughout the country – all it has ever taken is a phone call to discuss with the jurisdiction’s legal representation. Attorneys seem to have an understanding of what this type of prohibition truly means in respect to trying to defend against it. It is a no win.

Running into a similar circumstance with your new proposed post frame building? If so, please feel free to pass along the situation to me, chances are more than fair I can assist with its quick resolution.

Design Wind Speed Changes

Design Wind Speed Changes with Building Code Editions

Every three years a new version of the International Building Code (IBC) is printed, which brings with it the latest and greatest information for building design as approved by Code Officials. State and local permit issuing jurisdictions then can either adopt or amend the Code as they best see fit.

Even though the Code is updated on a three year cycle, some jurisdictions opt to continue to utilize earlier versions of the Code.

Provisions for design loads are set forth in Chapter 16 of the IBC.

There are significant changes to the design wind load requirements for fenestration between the 2009 IBC and the 2012 editions of the same code. These are due to significant changes to the wind load provision of ASCE (American Society® of Civil Engineers) 7 between the 2005 and 2010 edition.

The design wind load provisions of the 2005 and earlier editions of ASCE 7 were based upon allowable stress design of building components. The intent of this method was to provide loads to which the building components had a fairly high likelihood of being exposed during the service life of the building. The building components were then designed to remain serviceable (i.e. not require replacement) when subjected to this load.

The 2010 edition of ASCE 7 provides design wind load provisions which are based upon strength design of building components. This method provides loads which have a lower likelihood of occurring during the service life of the building. The building components are then designed not to fail (rupture) when subjected to this load.

This change in methodology results in higher design wind speeds and pressures. At first glance, this might give the appearance of requiring higher DP (Design Pressure) ratings. In actuality, the 2012 IBC contains provisions to multiply this new, higher load by a factor of 0.6 for the purpose of conversion to the more traditional method of determining the design wind pressure based upon allowable stress design. It is very important the builder, code official, manufacturer and anyone else involved in choosing or approving the structural building design for a particular application understand the higher design wind pressure provided by the 2012 IBC must be multiplied by this 0.6 conversion factor.

In most, but not all, cases this conversion results in required design pressure ratings which are roughly comparable to the more traditionally determined values.

ASCE7-10 also provides three different design wind speed maps. The different maps are based upon the assigned Risk Category of the building being designed.

  1. There is one map for buildings whose collapse would present a low risk to human life, such as barns and storage facilities.
  2. There is a second map for buildings whose collapse is considered to be a moderate hazard to human life. Most buildings fall within this category.
  3. There is a third map for buildings whose collapse is considered a high threat to human life, and for those which are considered essential facilities. The former includes assembly or education buildings designed to house groups of 250 or more people, some medical care facilities and any other buildings designed to house 5,000 people or more. Essential facilities include occupancies such as hospitals and police and fire stations, which are essential during emergency response situations.

The new maps result in higher design wind loads for buildings of moderate hazard to human life than for those of lower hazard. The highest design wind loads are given by the third map for buildings of high hazard to human life and essential facilities. Previous editions of ASCE 7 and the IBC also required these types of buildings to be designed to higher design loads, but the actual increase was applied in a different manner.

Considering a new post frame (pole) building? If you are looking at a building which is NOT designed by a registered design professional (RDP – engineer or architect) then there is an excellent chance the person or persons involved in the design do not understand the changes brought about by the newer editions of the Code and you could end up with an under designed building.

Under design can result in catastrophic failure – or even death. Don’t take the risk, demand an engineered building.

Your life or the lives of your loved ones could be at stake.

Proposed Building Code Change to Add to Construction Costs

During each 3-year-cycle of the International Building Code (IBC) and International Residential Code (IRC), there exists an opportunity to propose modifications and improve the codes to recognize new and innovative construction.  During the final two weeks in April, the code proposal hearings were held in Louisville, Kentucky where several hundred proposals were discussed and considered for inclusion in the code.

large-span-trusses-150x150While post-frame construction is typically used in agricultural applications which are often (and in my humble opinion sadly) considered exempt from code compliance, more and more post-frame construction is either residential housing (IRC) or commercial (IBC) in nature.  In these cases, changes which impact the code may have an effect on how post-frame buildings are constructed.

Eight proposals were identified by NFBA (National Frame Building Association) staff as having a potential impact on post-frame construction.  While the majority of these proposals were defeated, the following action should be noted:

S138-16: Submitted by the Structural Engineers Association, this proposal was approved and will require special inspection for wood trusses with a clear span of 60 feet or greater or an overall height of 60 inches or greater.  While the clear span is not a major issue, the 60 inch height may impact a number of projects creating new cost/scheduling issues.  This change is scheduled to be included in the 2018 IBC.

Having spent my entire adult life installing, designing, selling, building, delivering and purchasing wood trusses, it would seem ludicrous to require a special inspection for wood trusses with an overall height of 60 inches or greater. This would add an extra layer of inspection to nearly every building (not only post frame) project, with seemingly no apparent rationale other than the employment of a large number of people to perform these inspections (most likely the same structural engineers who made this proposal).

Trusses spanning 60 feet or more, are already required to have special inspections, under the IBC: https://www.hansenpolebuildings.com/2013/12/wide-span-trusses/.

What can you do? Contact your local Building Official today and ask them to vote to repeal this costly measure which does little or nothing to improve the safety of buildings.

Dear Pole Barn Guru: Why Didn’t You get the Snow Load Right?

Welcome to Ask the Pole Barn Guru – where you can ask questions about building topics, with answers posted on Mondays.  With many questions to answer, please be patient to watch for yours to come up on a future Monday segment.  If you want a quick answer, please be sure to answer with a “reply-able” email address.

Email all questions to: PoleBarnGuru@HansenPoleBuildings.com

DEAR POLE BARN GURU: I recently ordered a pole building kit package. The agreed snow load was 35. A minimum of 34 is required in our area. The calculations supplied are for 28, not 34. So now we are out another $800 and

back to square 2.

What can be done, and how fast? SNOWING IN SNOHOMISH

DEAR SNOWING: We’d all like to believe Building Department Plans Examiners are infallible. The reality is, the IBC (International Building Code) is a huge and complex document, which is further complicated by its references to numerous other outside documents.                  

The agreed upon snow load which you purchased, was 35 pounds per square foot (psf) as a GROUND SNOW LOAD (or Pg). The Code references a document called ASCE 7-10 (for the 2012 version of the Code). ASCE 7-10 gives the formula to convert Pg to flat roof snow load (Pf). This formula takes into account factors such as Building Importance, if Building is heated or not and the roof’s exposure to the wind. The roofing material also comes into play with the heating or not of the building.

 Pf is also adjusted for roof slope, to get to the design sloped roof snow load (Ps).

 In your particular case, our office made a call to your plans examiner who has now been happily educated.

 For further reading on this subject, please see the article I wrote for Structural Building Components magazine: https://sbcmag.info/article/2011/it-isnt-your-grandpas-barn-tips-technicians-designing-post-frame-trusses

DEAR POLE BARN GURU: I have an old metal barn that needs new doors and hardware. A pair of sliding doors that are each 10′ wide by 14′ tall. We had a storm that blew them off and damaged the tracks and channels. We live in Fowler, Colorado. Do you have a dealer here in Colorado? Or can we get them from you to install ourselves? Any information would be appreciated. CAUGHT IN COLORADO

 DEAR CAUGHT: Sliding doors can be a challenge in wind storms. If they are not correctly designed, installed, or kept closed and latched during high winds, they can all too easily end up as an unusable pile of rubbish. Sliding door frames which are built either partially or all from wood, are especially susceptible to failure under load.

 Hansen Pole Buildings provides sliding door systems and components direct to builders and end users in all 50 states. The doors are designed for the average individual to successfully assemble and install their own sliding doors, by following the detailed step-by-step instructions.

Call us and we will get you started on the path to replacing those doors.

DEAR POLE BARN GURU: Hello, I am helping a friend build and install sliding doors on his pole building. The building is otherwise complete. The door openings are pretty much ready to go as I can see. They are framed in and the upper track is installed. So here I come with a pile of steel siding, steel studs, track for SIDS and button of doors, rollers (pendant) and screws… The instructions he has are very vague. Can you provide me with any plans, prints, instructions of any kind please? Also a photo or diagram of what the finished product should look like?

They have a binder with instructions that supposedly came with the kit and your logo on the front of it. I’m not there at this time so if you need the model name/# I can send it to you this afternoon when I get there.  WONDERING IN WASHINGTON

DEAR WONDERING: While our sliding door systems are relatively simple for the average individual to install – having the detailed step-by-step instructions included in our Construction Guide, in hand would be a serious assist.

 The manual devotes 18 pages which include actual photos, as well as diagrams showing how to properly (as well as most quickly) assemble and install each component. Check the manual for these pages and then let me know if you still need help. Often people think the instructions come with the door and we’ve found having them in the Construction Guide makes them easier to find.

Use and Occupancy Group Classification Part II

As I said yesterday, in life, most everything is given some type classification whether it’s objective, such as motor vehicle operators’ licenses (automobile, commercial, motorcycle, etc.), or subjective, such as social status (wealthy, middle class, poor). Then there are those who are in “a class all by themselves.” My wife seems to think I fit in this category, which I take as a compliment! Buildings, like much of everything else, are classified, as well.  If you didn’t read yesterday’s blog – or if you did, review it quickly to get your head around the rest of the occupancy group discussion.

Yesterday I discussed “mixed group” classifications of buildings, such as fire stations and office buildings.

To continue, another occupancy group which relies on objective criteria is the High-Hazard Group H. Group H occupancies are assigned based on maximum quantities of materials which pose a physical or health hazard.

These materials may be used for manufacturing or processing, stored in the building, or generated as a product or byproduct through a process. Upon first glance, determining which H occupancy group is appropriate may seem to require a chemical engineering degree. However, material safety data sheets (MSDS) and the quantities involved allow for a practical guide. Discussing the project with a fire plans examiner at the building department can prove helpful as well.

Institutional (Group I) occupancies include buildings with occupants who are under supervised care, living in a controlled environment where they’re limited physically by either age or health, or they have personal liberties restricted by detention for penal or correctional purposes. Group I-3, which includes prisons, jails and correctional facilities, is further subdivided into “conditions.” However, unlike the occupancy subgroups, the five conditions are numbered with increasing risk to the higher numbers.

Residential (Group R) occupancies apply to buildings which are used for sleeping purposes, among the many other uses associated with residential uses. R-1 and R-2 groups apply to buildings which house occupants in large numbers. R-1 includes transient type housing consisting of hotels and motels, while R-2 housing is more of a permanent nature, such as apartments and dormitories. Groups R-3 and R-4 are required to comply with the requirements of the International Residential Code (IRC). R-3 occupancies include single detached houses and duplexes, and R-4 occupancies include assisted living and residential care facilities that have more than five, but less than 16, occupants, including staff.

Returning to mixed occupancies, designers of buildings involving multiple occupancies within the same structure have the option of selecting one of two types of mixed occupancies: Separated or non-separated uses. Mixed occupancies can be considered as “separated” because fire barriers of varying fire-resistance ratings are required between certain occupancies, or mixed occupancies can be non-separated, without any fire barriers.

There is a catch however, as the height and area requirements for each occupancy group used are to be applied to the entire building, and the most restrictive construction type will be applied to the entire building.

Allowable areas and building heights may be increased through consideration of automatic fire sprinkler protection and wide yards around the building.

Additionally, construction types are also of significant importance in properly applying the building code since they establish minimums based on building materials. The establishment of occupancy types is based on years of research and experience, and it is one of the essential building blocks in developing an effective building code.

And I can’t say this enough times…when in doubt take a trip to your friendly building department to discuss your building.  Take along a concise but complete list of all of the “uses” your new building will involve.  It will make your whole project slide along much smoother. These people want to see you build.  Their job is to ensure the health and safety of those using your new building.